SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 54: Quantum Coherence and Quantum Information Systems II

TT 54.3: Vortrag

Donnerstag, 30. März 2023, 15:30–15:45, HSZ 304

Linear response for pseudo-Hermitian Hamiltonian systems: Application to PT-symmetric qubits — •Mikhail V. Fistul, Leander Tetling, and Ilya M. Eremin — Ruhr-Universität Bochum, Bochum Germany

We develop the linear response theory formulation suitable for application to various pseudo-Hermitian Hamiltonian systems. The analytical expressions for the generalized temporal quantum-mechanical correlation function and the time-dependent dynamic susceptibility, χ(t), are derived [1].

We apply our results to two PT-symmetric non-Hermitian quantum systems: a single qubit and two unbiased/biased qubits coupled by the exchange interaction. For both systems we identify PT-symmetry unbroken and broken quantum phases and quantum phase transitions between them. The temporal oscillations of the dynamic susceptibility of the qubits polarization, χ(t), relate to ac induced transitions between different eigenstates, and we analyze the dependencies of the oscillations frequency and the amplitude on the gain/loss parameter γ and the interaction strength g.

Studying the time dependence of χ(t) we observe different types of oscillations, i.e., undamped, heavily damped and amplified ones, related to the transitions between eigenstates with broken (unbroken) PT-symmetry. These predictions can be verified in the microwave transmission experiments.

[1] L. Tetling, M. V. Fistul, and I. M. Eremin, Phys. Rev. B 106, 134511 (2022).